Can anybody suggest me an open-source code software that I can use for my research. I have to incorporate non-functional requirements (performance, security, etc.) into the architectural design and evaluate them. For this incorporation I need to extend UML representation. I have tried to do this with ArgoUML, but its latest version does not support sequence diagrams and I don't want to use its older versions. Can anybody help me by suggesting an open-source code software that I can use for my research.